100 THE ROTIFERA. 



is ovate, not so pyriform as in cornuta. The edges of the upper and lower plates come 

 closer together ; for the anterior two-thirds the edge of the dorsal plate is about level 

 with that of the ventral, but much exceeds it in length. The dorsal is straightly truncate 

 behind, with the margin on each side, following the ovate outline and descending much 

 farther, so as to form two points. The dorsal surface is somewhat coarsely tesselated, 

 like that of Cathypna rusticula, but with the pattern slightly different (PI. XXIV., 

 fig. 6). The whole surface appears as if irregularly crumpled, interfering with distinct 

 definition in spite of the transparency. The head is a low truncate cone, produced into 

 a number of slight frontal eminences, on which the locomotive cilia are arranged in tufts 

 or bundles. These do not appear to create sensible vortices in the surrounding water. 



This species is, I conjecture, the fig. 22 of Mr. J. E. Lord (" Microsc. News," June 

 1884, page 146), as M. cornuta is his fig. 21. I therefore distinguish it with his name. 

 I have met with it myself, on rare occasions recently, among decaying vegetation in the 

 water of Woolston Pond, and abundantly in water kindly sent me by Miss Saunders. 



Length, ^^ to T ^ inch. Habitat. Woolston ; Newbury ; Dundee (P.H.G.) : rare. 



There is a form, of which I am almost inclined to make a separate species, in general 

 like Lordii, but remarkable for the excessive length and slenderness of the toe, which 

 almost equals the length of the lorica. It may be but an extreme var. of the present 

 form. Yet the lorica seems to lack the square excavation behind, and to be more pyri- 

 form in outline, running off in front into broader lobes, as in lunaris. This I have found 

 in water sent me by Mr. Bolton from Button Park. P.H.G.] 



M. QUADKIDENTATA, Ehrcnberg. 

 (PI. XXV. fig. 3.) 



Monostyla quadridentata . . . Ehrenberg, Die In/us. 1838, p. 459, Taf. Ivii., fig. 5. 



[SP. CH. Lorica nearly circular, greatly depressed, especially behind ; front deeply 

 cleft, with two horn-like spines dccurved and expanding at their tips. 



The horns well distinguish this form. During retraction these are drawn together, 

 and made even to cross each other (fig. c). Besides these, and outside them, the 

 dorsal plate projects into a broad-based triangular point 011 each side; while the pectoral 

 margin forms a flexible membrane, very deeply cleft in the middle, and further deepened 

 at will. The hind part is exceedingly flattened, merging into the foot, of which the last 

 joint is cubical, with a central notch. Here is articulated the toe, rod-shaped, but that 

 the outline of each side, instead of being straight, is strongly waved : an appearance 

 which may possibly indicate the waves of a tenacious mucus. At one-fifth from the tip 

 a double shoulder, rounded rather than rectangular, leaves the usual acute claw. The 

 head protrudes (fig. b), much as described in cornuta. Of the trophi, the mallei (fig. d) are 

 remarkable for a conspicuous horn projecting upward from each angle. The gastric glands 

 are large; there is a large separate intestine, and also an ample contractile vesicle. 



Several examples have occurred to my observation. In one I was witness to a curious 

 phenomenon. A large shelled Infusory, Arcella vulgaris, was within the Monostyla, 

 though how it had managed to force its way in, I cannot imagine, for it almost filled the 

 cavity of the lorica. Its fleshy processes were protruding in front, and, by the death of 

 the Arcella, unable, I suppose, after it had devoured its host, to get out, these processes 

 gradually lengthened inordinately. It was a curious sight. P.H.G.] 



Length, y}^ to \. inch ; of lorica, T J ff to T ^- - inch. Habitat. Barking ; Stratford ; 

 Maidenhead; Hampstead (P.H.G.) ; among duckweed, in pools and ditches : rare. 



